1. Field of the Invention
The invention relates to a retractable device for flipping a large workpiece on a worktable. More particularly, it relates to pivoting arms, embedded below the surface of a finishing table, which extend upwardly to support and linearly translate the pivoting corner of the mattress, box spring, foundation or other cushion structure.
2. Description of the Prior Art
In the manufacture of mattresses, box springs, foundations or other cushion structures, the workpiece undergoes finishing, e.g. a tape edging process. The finishing process occurs on a finishing table having a work surface. Typically, the work surface has a smaller area than the larger mattresses, whereby the mattress extends off the work surface on all sides to provide easy access to all sides of the mattress. After the upper edge of the mattress is finished, the mattress needs to be flipped to allow finishing of the mattress"" lower edge.
The weight and size of the larger mattresses present a bulkiness that hinders handling and flipping. In the case of manual handling, flipping the mattress is difficult, dangerous and presents a production bottleneck since it is time consuming to support and flip the mattress safely. In the case of automated handling, the mattress is transported to a separate, outboard turning system. These outboard systems are expensive to acquire and install. In addition they occupy large areas in crowded manufacturing floors that adds to their maintenance costs.
An example of a stand alone turning devices may be seen in U.S. Pat. No. 3,967,723 and U.S. Pat. No. 4,175,655. The vertical extensions of these devices prevent their incorporation into work surfaces as they would interfere with the finishing process. A low profile turnover device may be seen in U.S. Pat. No. 4,890,717. However, this device is installed beneath a conveyor belt that provides a large surface to flip the workpiece onto. Accordingly, it would be desirable to provide a flipping device that allows a large workpiece to be flipped, in place, on a surface which is smaller than the workpiece. In addition, such a device should be embedded into the work surface, effectively hidden out of the way, when not in use.
It is therefore an object of the invention to flip a workpiece over onto a worksurface which may be smaller than the workpiece.
It is a further object of the invention to utilize supporting arms which are fully retractable below the worksurface during an idle state of the apparatus.
It is yet another object of the invention to incorporate a safety feedback sensor array to halt operation of the apparatus if the workpiece travels beyond a present distance outbound of the worksurface.
These and other related objects are achieved initially according to the invention by a method for flipping a workpiece on a worksurface having an edge. The method essentially employs a first step of raising a retracted arm out of the work surface to pivot the workpiece up and away from the edge; a second step of sliding the arm and the workpiece toward the edge; and a third step of guiding the workpiece through a 180xc2x0 rotation so that the workpiece is flipped, at least partially in place, back onto the worksurface. The arms engage a lower corner of the workpiece farthest from the edge, and in a practical embodiment of same a support arm contacts a lower surface of the workpiece and a bracket arm contacts a side surface of the workpiece farthest from the edge. Computer control of pneumatic drives coordinate movement of the arms.
A sensor array provides sensor data to the computer control about the position of the workpiece, and halts operation of the pneumatic drives if the workpiece travels a present distance beyond a periphery of the worksurface. Ideally, the sensor data is obtained from an optical sensor array arranged a preset distance outbound of the worksurface periphery.
The method according to the invention is carried out by a material handling system wholly mounted within a worktable having a worksurface with an edge. The system includes an arm having an initial position within the worktable below the worksurface; a mechanical drive coupled to the arm for raising the arm to pivot the workpiece up and away from the edge and for subsequently sliding the arm and the workpiece toward the edge; and a catcher plate for guiding the workpiece through a 180 degree rotation so that the workpiece is flipped, at least partially in place, back onto the worksurface. Pneumatic drives elevate a retracted support arm into engagement with a lower surface of the workpiece, and a retracted bracket arm into engagement with a side surface of the workpiece farthest from the edge.
In a practical embodiment a microprocessor is coupled to the pneumatic drives for coordinating movements of the support and bracket arm and the catcher plate. An optical sensor array is coupled to the microprocessor for providing sensor data about the position of the workpiece in relationship to the worksurface. Upon receiving sensor data that the workpiece has encountered the optical sensor array, the microprocessor halts operation of the drives.